package learn_concurrent._13;

import java.sql.Array;
import java.sql.Blob;
import java.sql.CallableStatement;
import java.sql.Clob;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.NClob;
import java.sql.PreparedStatement;
import java.sql.SQLClientInfoException;
import java.sql.SQLException;
import java.sql.SQLWarning;
import java.sql.SQLXML;
import java.sql.Savepoint;
import java.sql.Statement;
import java.sql.Struct;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.Executor;
import java.util.concurrent.atomic.AtomicIntegerArray;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class T1 {

	final static Logger logger = LoggerFactory.getLogger(T1.class);

	public static void main(String[] args) {
		DBPool pool = new DBPool(2);
		
		for (int i = 0; i < 5; i++) {
			new Thread(() -> {
				Connection conn = pool.borrow();
				try {
					Thread.sleep(1000);
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
				pool.free(conn);
				
			}).start();
		}
	}

}

class DBPool {
	private final static Logger logger = LoggerFactory.getLogger(DBPool.class);

	private Connection[] connections;
	private AtomicIntegerArray states;
	private final int size;

	public DBPool(int size) {
		connections = new Connection[size];
		states = new AtomicIntegerArray(new int[size]);
		this.size = size;
		for (int i = 0; i < size; i++) {
			connections[i] = new MockConnection(i + "");
		}
	}

	public Connection borrow() {
		while (true) {
			for (int i = 0; i < size; i++) {
				if (states.get(i) == 0) {
					if(states.compareAndSet(i, 0, 1)) {
						logger.debug("borrow -> {}", connections[i]);
						return connections[i];
					}
				}
			}
			synchronized (this) {
				try {
					logger.debug("wait......");
					this.wait();
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
			}
		}
	}

	public void free(Connection conn) {
		for (int i = 0; i < size; i++) {
			if (connections[i] == conn) {
				states.set(i, 0);
				logger.debug("free -> {}", conn);
				synchronized (this) {
					this.notifyAll();
				}
				break;
			}
		}
	}
}

class MockConnection implements Connection {

	private final String name;

	public MockConnection(String name) {
		this.name = name;
	}

	@Override
	public String toString() {
		return "MockConnection [name=" + name + "]";
	}

	@Override
	public <T> T unwrap(Class<T> iface) throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public boolean isWrapperFor(Class<?> iface) throws SQLException {
		// TODO Auto-generated method stub
		return false;
	}

	@Override
	public Statement createStatement() throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public PreparedStatement prepareStatement(String sql) throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public CallableStatement prepareCall(String sql) throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public String nativeSQL(String sql) throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public void setAutoCommit(boolean autoCommit) throws SQLException {
		// TODO Auto-generated method stub

	}

	@Override
	public boolean getAutoCommit() throws SQLException {
		// TODO Auto-generated method stub
		return false;
	}

	@Override
	public void commit() throws SQLException {
		// TODO Auto-generated method stub

	}

	@Override
	public void rollback() throws SQLException {
		// TODO Auto-generated method stub

	}

	@Override
	public void close() throws SQLException {
		// TODO Auto-generated method stub

	}

	@Override
	public boolean isClosed() throws SQLException {
		// TODO Auto-generated method stub
		return false;
	}

	@Override
	public DatabaseMetaData getMetaData() throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public void setReadOnly(boolean readOnly) throws SQLException {
		// TODO Auto-generated method stub

	}

	@Override
	public boolean isReadOnly() throws SQLException {
		// TODO Auto-generated method stub
		return false;
	}

	@Override
	public void setCatalog(String catalog) throws SQLException {
		// TODO Auto-generated method stub

	}

	@Override
	public String getCatalog() throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public void setTransactionIsolation(int level) throws SQLException {
		// TODO Auto-generated method stub

	}

	@Override
	public int getTransactionIsolation() throws SQLException {
		// TODO Auto-generated method stub
		return 0;
	}

	@Override
	public SQLWarning getWarnings() throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public void clearWarnings() throws SQLException {
		// TODO Auto-generated method stub

	}

	@Override
	public Statement createStatement(int resultSetType, int resultSetConcurrency) throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency)
			throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency) throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public Map<String, Class<?>> getTypeMap() throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public void setTypeMap(Map<String, Class<?>> map) throws SQLException {
		// TODO Auto-generated method stub

	}

	@Override
	public void setHoldability(int holdability) throws SQLException {
		// TODO Auto-generated method stub

	}

	@Override
	public int getHoldability() throws SQLException {
		// TODO Auto-generated method stub
		return 0;
	}

	@Override
	public Savepoint setSavepoint() throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public Savepoint setSavepoint(String name) throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public void rollback(Savepoint savepoint) throws SQLException {
		// TODO Auto-generated method stub

	}

	@Override
	public void releaseSavepoint(Savepoint savepoint) throws SQLException {
		// TODO Auto-generated method stub

	}

	@Override
	public Statement createStatement(int resultSetType, int resultSetConcurrency, int resultSetHoldability)
			throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency,
			int resultSetHoldability) throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency,
			int resultSetHoldability) throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public PreparedStatement prepareStatement(String sql, int autoGeneratedKeys) throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public PreparedStatement prepareStatement(String sql, int[] columnIndexes) throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public PreparedStatement prepareStatement(String sql, String[] columnNames) throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public Clob createClob() throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public Blob createBlob() throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public NClob createNClob() throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public SQLXML createSQLXML() throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public boolean isValid(int timeout) throws SQLException {
		// TODO Auto-generated method stub
		return false;
	}

	@Override
	public void setClientInfo(String name, String value) throws SQLClientInfoException {
		// TODO Auto-generated method stub

	}

	@Override
	public void setClientInfo(Properties properties) throws SQLClientInfoException {
		// TODO Auto-generated method stub

	}

	@Override
	public String getClientInfo(String name) throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public Properties getClientInfo() throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public Array createArrayOf(String typeName, Object[] elements) throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public Struct createStruct(String typeName, Object[] attributes) throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public void setSchema(String schema) throws SQLException {
		// TODO Auto-generated method stub

	}

	@Override
	public String getSchema() throws SQLException {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public void abort(Executor executor) throws SQLException {
		// TODO Auto-generated method stub

	}

	@Override
	public void setNetworkTimeout(Executor executor, int milliseconds) throws SQLException {
		// TODO Auto-generated method stub

	}

	@Override
	public int getNetworkTimeout() throws SQLException {
		// TODO Auto-generated method stub
		return 0;
	}

}
